1. Field of the Invention
The present invention relates to a steering system for a small boat.
2. The Related Art of the Invention
As a steering system for a conventional small boat such as a boat with an outboard motor, there has been proposed a steering system in which a power is assisted by an electric motor as disclosed in Japanese Patent Serial No. 2652788.
In this conventional steering system, an operation of a steering wheel located in a driver's seat is transmitted to an outboard motor steerably supported in a rear side of the boat by a wire and the outboard motor is rotated in accordance with a steering amount of the steering wheel. On the other hand, a rotating force of the electric motor in a power-assisted mechanism rotates the outboard motor through a reduction gear. Herein an output signal of a steering force sensor to sense a steering transmission force acting on the wire, a motor rotation number signal of the outboard motor and the like are detected. An assist force of the electric motor is controlled in accordance with the signals by an electric control unit.
However, since the electric motor or the steering force sensor are arranged in the vicinity of the outboard motor in the conventional steering system, there is a need for improving a water proofing property so as to prevent water rolled up by a propeller or the like from entering into the electric motor or the steering force sensor. And the mounting of them is complicated, thereby to increase costs of the steering system.
And an operating force of the wire pushed and pulled by the steering of the steering wheel is sensed by the steering force sensor. Therefore, the steering force that can be sensed by the steering force sensor reduces or varies by friction generated caused by the wire operation, deteriorating the accuracy of the sensor. As a result, the assist force is restricted and therefore, there is a limit to reducing the steering force and improving a feeling of the steering.
In view of the above, there exists a need for a steering system for a small boat which overcomes the above-mentioned problems in the related art. The present invention addresses this need in the related art and also other needs, which will become apparent to those skilled in the art from this disclosure.